If you literally need a "paper" game to play with a friend offline, these classic paper-and-pencil games are popular alternatives to digital versions: GitHub Game Off Submission Stream for Open Source Friday #2
Disclaimer: Availability of specific games changes as developers update repositories. If a link is broken, check the developer’s main GitHub page for a new deployment. 2 player games github.io
GitHub Pages is a static site hosting service that takes HTML, CSS, and JavaScript files straight from a repository on GitHub and publishes them as a website. This technical simplicity is the driving force behind its popularity for 2-player games. If you literally need a "paper" game to